This application claims priority under 35 U.S.C. xc2xa7xc2xa7119 and/or 365 to application Ser. No. 199 62 386,4 filed in Germany on Dec. 23, 1999; the entire content of which is hereby incorporated by reference.
The present invention relates to a method for supplementing a saturated steam generation system having at least one steam turbine set in a steam power plant which is designed for high live steam parameters. It also relates to a steam power plant supplemented using this method.
For various reasons, the state of a steam generator may change, in particular after a prolonged operating period, in such a way that the steam generator can only continue to be operated at reduced output or with changed parameters.
For example, it is possible that the output or specified parameters of a steam generator will not be reached because of the heating surfaces being highly contaminated by deposits.
Particularly in a nuclear power plant, components in the nuclear area are additionally aged by the exposure to radiation. Furthermore, nuclear technology is the subject of intense political discussion, which may cause the statutory framework conditions to change. One consequence may be that it is no longer possible or permissible for the reactor to be operated at its full power density, and as a result the output from the steam generation will fall, the flexibility of the plant will be restricted and the like.
If a steam generator has to be operated at reduced output, and the water/steam cycle and therefore the steam turbine set of the power plant are no longer fully loaded, restrictions arise with regard to the operating methods which were originally permitted and the like. The result is losses in the electric power generated, i.e. financial losses for the operator, for example, of the power plant.
When supplementing saturated steam generation systems of reduced output having steam turbine sets, the supplementing procedure at the same time aims to modernize the installation by raising the steam parameters in order to increase both the output and the efficiency of the overall power plant, comprising the saturated steam generation system and the steam turbine sets.
The invention is therefore based on the object of providing a method for supplementing a saturated steam generation system having at least one steam turbine set, according to which, while the original plant technology is maintained, the at least one steam turbine set can continue to be as fully loaded as possible with a reduced output from the saturated steam generation system.
This supplementing process is advantageously to lead to the output being increased but also, at the same time, to the efficiency of the entire steam power plant being increased.
The invention is to be suitable in particular for supplementing a nuclear saturated steam generation system having at least one steam turbine set.
In a first embodiment of the method, this is achieved, according to the invention, in that the saturated steam generation system is supplemented with at least one gas turbine set, at least one heat recovery steam generator, at least one topping steam turbine and at least one steam mixing component, the exhaust gas from the at least one gas turbine of the at least one gas turbine set is utilized for steam generation in the at least one heat recovery steam generator, the steam which is generated in the at least one heat recovery steam generator is fed via a live steam line to the at least one topping steam turbine, and the exhaust steam from the at least one topping steam turbine is fed via an exhaust steam line to the at least one steam mixing component, in which at least one steam mixing component steam originating from the saturated steam generation system is mixed with steam originating from the at least one topping steam turbine, and the steam mixture is provided to the at least one steam turbine set. The exhaust steam states of the at least one topping steam turbine are within the ranges which are permissible for operation of the at least one steam turbine set.
In a second embodiment of the method, the at least one steam turbine set has a saturated steam intermediate pressure steam turbine, a separator, a reheater and a low pressure steam turbine, and the at least one heat recovery steam generator has a reheater. The exhaust steam from the saturated steam intermediate pressure steam turbine of the at least one steam turbine set is at least in part reheated on the mass flow side in the reheater of the at least one heat recovery steam generator, and the reheated steam is provided to the at least one steam turbine set.
In a third embodiment of the method, the at least one topping steam turbine has a high pressure part and an intermediate pressure part, and the at least one heat recovery steam generator has a reheater. The exhaust steam from the high pressure part of the at least one topping steam turbine is reheated in the reheater of the at least one heat recovery steam generator and, after the reheating, is fed to the intermediate pressure part of the at least one topping steam turbine. The exhaust steam from the intermediate pressure part of the at least one topping steam turbine is fed via the exhaust steam line to the at least one steam mixing component of the at least one steam turbine set.
A steam power plant which has been supplemented according to a first embodiment of a plant for carrying out the method, which plant has a saturated steam generation system and at least one steam turbine set which is supplied with steam by this system, is distinguished by at least one gas turbine set, at least one heat recovery steam generator, at least one topping steam turbine and at least one steam mixing component, which steam mixing component is in communication on the inlet side with the saturated steam generation system and with the at least one topping steam turbine and on the outlet side with at least one part of the steam turbine set.
According to a second embodiment of the plant for carrying out the method, which plant has a saturated steam generation system and at least one steam turbine set, the plant is distinguished by the fact that the at least one heat recovery steam generator has a reheater and the at least one steam turbine set has a saturated steam intermediate pressure steam turbine, a separator, a reheater and a low pressure steam turbine, at least one steam mixing component is arranged between the saturated steam generation system and the at least one steam turbine set, which component is in communication on the inlet side with the saturated steam generation system and the at least one topping steam turbine and on the outlet side with the at least one steam turbine set, which saturated steam intermediate pressure steam turbine is in communication, via a cold reheat steam line, with the reheater of the at least one heat recovery steam generator, from which there leads a hot reheat steam line which runs to the at least one low pressure steam turbine.
According to a third embodiment of the plant for carrying out the method, which plant has a saturated steam generation system and at least one steam turbine set, this plant is distinguished by the fact that the at least one heat recovery steam generator has a reheater, and the at least one topping steam turbine has a high pressure part and an intermediate pressure part, the high pressure part being connected on the exhaust steam side, via a cold reheat steam line, to the reheater of the at least one heat recovery steam generator, the hot reheat line of which is connected to the intermediate pressure part of the at least one topping steam turbine, the exhaust steam line of which is in communication with at least one part of the steam turbine set.
Once the supplementing is complete, the plant comprises at least two independent generator units, having
different dynamic performance
different efficiencies of energy generation, and
if appropriate different fuels and fuel prices.
As a result, there is further freedom in terms of the operating method and the economics of the plant.
The advantages of the invention are that, despite a reduced output from the saturated steam generation system, the existing steam turbine set, which is designed for saturated steam conditions, can continue to be operated under full load, and the overall output and efficiency of the power plant can be increased. In addition, the flexibility of the power plant rises through having two independent generator units. Particularly for nuclear power plants, the result is a plant which involves minimal investment.
Furthermore, particularly in the case of a nuclear power plant, it is possible for the nuclear part of the power plant and the gas turbine part to operate independently. In addition, the power plant represents a first stage of conversion from a nuclear power plant to a combined-cycle power plant, with the aim of subsequently shutting down the nuclear part.